In electronics testing systems, such as an integrated circuit (IC) or a system on a chip (SOC) test system, the electronic circuit testers typically test the performance of an IC, SOC or similar device. An electronic circuit tester may be used to test finished packaged devices or integrated circuits at various stages of the manufacture of the device or integrated circuit, from the initial wafer processing stage to the final packaging stage. A conventional tester typically includes a test head and electronic test and measurement instruments. The electronic test and measurements instruments, may be contained within the test head or in equipment racks that are electrically connected to the test head. The test head typically interfaces with a device or an integrated circuit through a printed circuit board known as a load board. In these test systems, the load board is used to provide an electrical and mechanical interface between the tester and the device-under-test (DUT). The load board extends measurement electronics of the automated test system to the pins or pads of the DUT. A custom load board is usually required for each unique DUT or family of DUTs.
Since the electronic circuit tester can be employed to test both packaged devices and integrated circuits in many forms, the test head is usually mounted by pivotal connections to a dolly or to the instrument rack. The pivotal connections enable the test head to be positioned in many positions including an approximately upward facing horizontal position so that the appropriate load board can be mounted on the test head of the electronic circuit tester by an operator. The test head can also be pivoted to any of many angular positions, such as to a substantially vertical position so that the load board can interface with an automated material handler, for example, to test packaged devices or integrated circuits. The automated material handler feeds each packaged device or integrated circuit to be tested (either or both of which hereafter referred to as a device or a DUT) to the electronic circuit tester.
A conventional tester 10, is shown in FIG. 1. Tester 10 comprises a test head 12 electrically connected by cables routed through a conduit 14 to rack(s) 16 of electronic test and measurement instruments, such as AC and DC signal generators for applying electrical signals to a device or integrated circuit interfaced to the test head 12, and signal analyzers, for example, a network analyzer, spectrum analyzer, oscilloscope, or other waveform digitizing or signal processing equipment, for measuring the response(s) to applied signals. Test head 12 may include circuitry that performs distribution of electrical signals, signal separation, frequency translation, amplification, attenuation, switching, or other conditioning or modification of electrical signals prior to being routed to the rack 16 or to a device or integrated circuit being tested.
Test head 12 interfaces to a device or integrated circuit through a load board 18 and a fixture board 20 mounted to the test head 12. Alternatively, prior to installation of fixture board 20, a calibration board (not shown), having a configuration similar to the fixture board may be connected to the test head 12 for calibrating the test head 12. The configuration of the load board 18 depends on the type or family of device or integrated circuit being tested, such as an analog or digital electronic circuit, while the configuration of the fixture board 20 is generally specific to the family or particular device or integrated circuit under test (DUT).
Fixture board 20 interfaces to a device-under-test (DUT) board 22 that may comprise inductors, capacitors, and other electronic components or circuit mounted to or fabricated on the DUT board for decoupling, filtering attenuating or otherwise modifying electrical signals transmitted to or received from a device or integrated circuit under test. Finally, the DUT board 22 is connected to a socket 24 for effecting electrical connection(s) between tester 10 and the actual electronic circuit or device-under-test (DUT), such as a packaged device or integrated circuit 26. Alternatively, socket 24 may be mounted directly to the load board 18.
Test head 12 is mounted to a dolly 28. Test head 12 may be mounted by pivotal connections 30 to dolly 28. Pivotal connections 30 enable test head 12 to be positioned in an approximately upward facing horizontal position so that the appropriate load board 18 and calibration or fixture board 20 and DUT board 22 with socket 24 can be mounted to test head 12 of tester 10 by an operator. Test head 12 may be pivoted to any angular position so that socket 24 may interface with an automated material handler 32, for example, which rapidly feeds each DUT 26 to the tester 10 to be tested.
Alternatively, a wafer probe (not shown) may be substituted for the socket 24 mounted to the DUT board 22. Pivotal connections 30 enable test head 12 to be pivoted to an inverted position to test devices or integrated circuits on a wafer (not shown) at a wafer probing stations (not shown).
In order to interface socket 24 to the automated material handler 32, or a wafer probe (not shown) at a wafer probing station (not shown), a frame 34 is mounted to test head 12. A handler mounting plate 36 that mates with frame 34 is mounted to the automated material handler 32 or wafer probing station (not shown) to align test head 12 with the handler or station so that packaged devices or integrated circuits or devices or integrated circuits on wafer can be tested.
Unlike most of the printed circuit boards and electronics in a test system 10, the load board 18 is not enclosed within a chassis, which means that load boards 18 are susceptible to electromagnetic interference (EMI) that would normally be attenuated by a chassis. It is not uncommon to find very high levels of EMI on test floors at IC test companies from area cellular telephone relay and broadcast towers or other local industrial activity. One potential method of EMI shielding is to build a screen room around the tester. However, as testers are very large, this is an expensive solution, inconvenient, wastes production or test floor space and reduces the flexibility of production or tester floor space.